Polyvinyl acetal resin film for laminated glass

Abstract

A polyvinyl acetal resin film for laminated glass,a viscosity of toluene/ethanol=1/1 (by mass ratio) solution of a polyvinyl acetal resin in a resin composition constituting the polyvinyl acetal resin film with a concentration of 10% by mass, measured at 30 rpm and 20° C. by using a Brookfield-type (B-type) viscometer, being more than 200 mPa·s,the polyvinyl acetal resin film comprising a plasticizer in an amount of 0 to 20% by mass based on a total mass of the resin composition constituting the polyvinyl acetal resin film, andthe polyvinyl acetal resin film having a thickness of 10 to 350 μm.

The invention claimed is: 
     
       1. A polyvinyl acetal resin film for laminated glass, wherein:
 a viscosity of toluene/ethanol=1/1 (by mass ratio) solution of a polyvinyl acetal resin in a resin composition constituting the polyvinyl acetal resin film with a concentration of 10% by mass, measured at 30 rpm and 20° C. by using a Brookfield-type (B-type) viscometer, being more than 200 mPa·s, 
 the polyvinyl acetal resin film comprising a plasticizer in an amount of 0 to 20% by mass based on a total mass of the resin composition constituting the polyvinyl acetal resin film, 
 wherein molecular weight distribution of the polyvinyl acetal resin in the resin composition constituting the polyvinyl acetal resin film is 2.7 or more, 
 wherein the amount of the plasticizer is 0 to 15 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin, 
 wherein the amount of the polyvinyl acetal resin contained in the resin composition is 50% by mass or more based on the total mass of the resin composition, and 
 the polyvinyl acetal resin film having a thickness of 10 to 350 μm. 
 
     
     
       2. The polyvinyl acetal resin film according to  claim 1 , wherein a value indicating heat creep resistance measured with the polyvinyl acetal resin film bonded to a 0.76 mm thick plasticized polyvinyl butyral resin layer which contains 72% by mass of polyvinyl butyral resin having an acetalization degree of 69 to 71 mol % and containing a vinyl acetate unit as an acetyl group in an amount of 1 mol % or less and 28% by mass of triethylene glycol-bis-(2-ethylhexanoate) is 10 mm or less,
 the value indicating heat creep resistance being measured by a method of bonding the polyvinyl acetal resin film and the plasticized polyvinyl butyral resin layer, cutting the bonded polyvinyl acetal resin film and plasticized polyvinyl butyral resin layer into a sample having dimensions of 100 mm wide and 270 mm long, arranging and bonding the sample so as to be fit between glass A and glass B that have a width of 100 mm, a length of 300 mm and a thickness of 3 mm and are shifted by 30 mm in a length direction such that the glass A, the polyvinyl acetal resin film, the plasticized polyvinyl butyral resin layer, and the glass B are arranged in this order, bonding an iron plate of 1 kg with an adhesive to a surface of the glass B, which is opposite to a surface bonded to the plasticized polyvinyl butyral resin layer, to obtain a sample with the iron plate, and, after the sample with the iron plate is left in a thermostat at 100° C. for 1 week in a state in which a portion protruding 30 mm in the length direction faces upward and the glass A is fixed such that an angle of the sample with the iron plate is 80 to 90° with respect to a horizontal plane and a portion of the glass B to which the iron plate is bonded serves as an upper portion or an upper surface of the sample, measuring a distance (mm) by which the glass B has deviated. 
 
     
     
       3. The polyvinyl acetal resin film according to  claim 1 , wherein the polyvinyl acetal resin in the resin composition constituting the polyvinyl acetal resin film is a mixture of at least two polyvinyl acetal resins having different viscosity average polymerization degrees, or an acetalized product of a mixture of at least two polyvinyl alcohol-based resins having different viscosity average polymerization degrees. 
     
     
       4. The polyvinyl acetal resin film according to  claim 1 , wherein the resin composition constituting the polyvinyl acetal resin film contains an alkali metal salt and/or an alkaline earth metal salt. 
     
     
       5. The polyvinyl acetal resin film according to  claim 1 , wherein a hydroxyl group amount of the polyvinyl acetal resin in the resin composition constituting the polyvinyl acetal resin film is 26 to 34 mol %. 
     
     
       6. The polyvinyl acetal resin film according to  claim 1 , wherein the amount of the plasticizer is 0 to 5 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin. 
     
     
       7. The polyvinyl acetal resin film according to  claim 1 , wherein the polyvinyl acetal resin film comprises a functional layer on at least one side of the polyvinyl acetal resin film. 
     
     
       8. The polyvinyl acetal resin film according to  claim 7 , comprising no adhesive layer between the polyvinyl acetal resin film and the functional layer. 
     
     
       9. The polyvinyl acetal resin film according to  claim 7 , wherein the functional layer is a conductive layer. 
     
     
       10. The polyvinyl acetal resin film according to  claim 9 , comprising another polyvinyl acetal resin film on a surface having the conductive layer of the polyvinyl acetal resin film. 
     
     
       11. The polyvinyl acetal resin film according to  claim 9 , wherein the conductive layer is based on metal foil. 
     
     
       12. The polyvinyl acetal resin film according to  claim 9 , wherein the conductive layer has a linear, grid-like or net-like shape. 
     
     
       13. The polyvinyl acetal resin film according to  claim 9 , wherein the conductive layer comprises a plurality of linear conductive materials having a line width of 1 to 30 μm. 
     
     
       14. The polyvinyl acetal resin film according to  claim 9 , wherein one or both sides of the conductive layer are subjected to a low-reflectance treatment. 
     
     
       15. The polyvinyl acetal resin film according to  claim 9 , comprising a bus bar connected to the conductive layer. 
     
     
       16. The polyvinyl acetal resin film according to  claim 15 , wherein the bus bar is integrally formed with the conductive layer. 
     
     
       17. A laminate comprising the polyvinyl acetal resin film according to  claim 7  and a plasticized polyvinyl acetal resin layer between a plurality of transparent substrates. 
     
     
       18. The laminate according to  claim 17 , wherein a difference between a hydroxyl group amount of the polyvinyl acetal resin in the resin composition constituting the polyvinyl acetal resin film and a hydroxyl group amount of the polyvinyl acetal resin in the resin composition constituting the plasticized polyvinyl acetal resin layer is 4% by mass or less as a difference in percentage by mass of vinyl alcohol units. 
     
     
       19. The laminate according to  claim 17 , wherein the plasticized polyvinyl acetal resin layer has at least one function selected from the group consisting of a specific wavelength light shielding function, a heat shielding function, a sound insulating function, a light emitting function, a display function and a double image prevention function. 
     
     
       20. A method of producing the polyvinyl acetal resin film according to  claim 7 , comprising applying a material constituting the functional layer by coating, printing or lamination on at least one side of the polyvinyl acetal resin film.